Many adhesives are regularly used to facilitate temporarily or permanently bonding like and unlike elements. Types of adhesives commonly used include reactive, anaerobic, pressure sensitive and thermosetting. All have limitations which dictate their preferred usage.
As used herein, the term "pressure sensitive adhesive" refers to an adhesive that is tacky at ambient or room temperatures. Pressure sensitive adhesives are often used as the adhesive means in various closure systems. The pressure sensitive adhesive on a closure system must be covered with a release liner during shipping or a storage to prevent a premature permanent bond from occurring. The release liner completely isolates the intended exposed area of the adhesive. This complete isolation of the adhesive is not always desirable.
A particular application of this type of temporary to permanent adhesive closure system is in the area of pipe insulation sleeves. Pipes which are used in dwellings and commercial buildings are often covered with an insulation sleeve or wrap. The insulation sleeves are typically installed for improved energy efficiency or safety. The pipes may be made of copper, plastic, cast iron, or other like materials. The insulation sleeve or wrap is generally a cylindrically shaped tubular section having a centrally disposed channel along its longitudinal axis to receive the pipe. The insulation sleeve may be constructed of a flexible elastomeric foam such as vinyl nitrile, or various other insulating materials such as a glass fiber layer with a protective overcoating. Each section has a slit that extends radially from the inside diameter of the tube to its outer surface, and longitudinally along the entire length of the sleeve. This slit, herein referred to as the access slit, affords an opening, or access for the pipe to enter the sleeve so as to reside within the central channel. Normally the insulation sleeve will come in 6 to 8 foot lengths with internal diameters ranging from 1 to 8 inches and external diameters ranging from 2 to 10 inches. Typically the tubular insulation is cut to length and installed around the pipe by means of the longitudinal access slit. Once the sleeve is in place, the opposite walls of the access slit are brought together and sealed. Typically, sealing is accomplished through the use of a pressure sensitive adhesive applied to one or both of the opposite faces of the access slit. An alternate method of closure comprises a longitudinally extending flap, herein referred to as a closure flap, on the outer surface of one side of the access slit, the closure flap incorporates a pressure sensitive adhesive on the inner side of the flap. The flap is pressed into engagement with the outer surface of the other side of the access slit, thereby forming the adhesive bond.
Adhesive is typically applied during manufacture of the insulation sleeve and a solid release liner is applied to the adhesive. It is known to use a solid release liner that completely covers and isolates the exposed side of the adhesive to allow the insulation sleeve to be shipped and installed before a permanent bond is achieved. Alternately, the adhesive can be applied during the installation of the insulation sleeve, by the installer. Both of these methods require the insulation sleeve to be shipped with the access slit in an unbonded or open position. An insulation sleeve shipped with the access slit in this open position, is less rigid than if the access slit were bonded in the closed position. Because the open or unbonded insulation sleeve is less rigid than a closed or unified sleeve, the open sleeve may permanently deform from its own weight and the weight of the sleeves stored above it. This deformation causes numerous problems including sleeves that do not fit in the intended pipe, and internal stresses that occur when the deformed sleeve is placed on the pipe, causing the adhesive joint to prematurely fail.